Special thanks to Jaroslaw Komasinski (1nd sample) and Johannes Matzke (2nd sample) for providing this lens!

Introduction

The Canon EF 100mm f/2.8 USM macro was introduced back in march 2000 replacing the old EF 100mm f/2.8
macro (featuring a classic micro motor). On APS-C DSLRs the
field-of-view resembles a 160mm full format equivalent. The primary application
of the lens is, obviously, macro photography but it's not limited to that - infinity focus is possible.

Note: the image above shows the lens with an (optional) filter attached and the (also optional) lens hood has been cut down in length.

The lens has been completely redesigned into a true IF (internal focus) construction that
does not extend when focusing to macro distances. This is highly unusual for a 100mm macro lens.
The front element does not rotate so using a polarizer is not problem. Typical for ring-type USM
lenses full-time manual override is always possible in one-shot AF mode. The AF speed is blazingly
fast (another unique point) but Canon still provided a focus limiter in order to avoid any AF
hunting into the extreme macro range when operating the lens at normal focus distances.
The minimal focus distance is 0.31m (149mm working distance) resulting in a max. magnification of 1:1.
The broad, rubberized focus ring and has smooth, pleasant operation. The build quality is very decent
with a metal mount and an outer barrel made of good quality plastics.
The optical construction is made of 12 elements in 8 groups without any special elements.
The lens features 8 aperture blades. Typical for all true macro lenses it features a floating
system in order to achieve a constant performance throughout all focusing distances. The filter
size is 58mm. With a weight of 600g and a size of 79x119mm it is fairly compact and about comparable
to the rest of the gang in this class.

It also a possible to use an optional tripod mount which can be attached to the rear of the lens.
While not really required the tripod mount provides a better balance - otherwise the camera
lens combination tends to be somewhat front loaded specifically when used on light-weight DSLRs.